C1s, Human, mAb M241,Hycult Biotech,HM2109

Monoclonal antibody M241 reacts with an epitope on human C protein activated C1s, a subcomponent of the first component of C (C1). Activated C1s is a glycosylated single-polypeptide zymogen of 85 kD. Activation of the proenzyme C1s occurs through cleavage by the active form of C1r. The activated protease, activated C1s, consists of a disulfide-linked H chain and a L chain. Activated C1s is a serine protease and its catalytic site is located in the L chain. Activation of the classical C pathway is triggered by activated C1s which cleaves C4 and C2 to form the C3 convertase, C4bC2a. The epitope recognised by the antibody M241 is domain IV and/or V of the gamma-domain of activated C1s. Monoclonal antibody M241 blocks C4 activation and C4 binding to activated C1s. The antibody binds specifically to the active centre of C1s.